The present invention relates to an ion-implantation apparatus and a method of ion-implantation by use of this apparatus, and more particularly to an ion-implantation apparatus capable of suppressing a shift of an ion-implantation amount due to an out gas from a resist over a wafer and a method of ion-implantation by use of this apparatus.
FIG. 1 is a schematic cross sectional view illustrative of a conventional ion-implantation apparatus. The conventional ion-implantation apparatus has the following elements. A chamber 1 is provided which accommodates a semiconductor wafer 2 over which a resist is provided. A pressure gage 5 is also provided on the chamber 1 for measuring an internal pressure of the chamber 1. A dose counter 6 is also provided in the chamber 1 for receiving an ion-beam 3 and measuring a dose of the ion-beam 3.
If the ion-beam 3 is irradiated onto the resist over the semiconductor wafer 2, then an out-gas from the resist neutralizes or ionizes the ion-beam 3, whereby an amount of the ion-implantation is shifted from when the ion-beam 3 is irradiated onto the semiconductor wafer free of resist.
It is necessary to maintain the measurement to the internal pressure of the chamber by the vacuum gage during the ion-implantation process for the purpose of making a real time calculation of the neutralization or ionization of the ion-beam 3 so as to correct the amount of ion-implantation. The neutralization or ionization of the ion-beam 3 varies depending upon the kinds of ion, the beam current, the ion-implantation energy, and the resist material, for which reason the calculation of the neutralization or ionization of the ion-beam 3 are needed for every times.
In the above circumstances, it had been required to develop a novel ion-implantation apparatus and a method of ion-implantation by use of this apparatus free from the above problem.
Accordingly, it is an object of the present invention to provide a novel ion-implantation apparatus free from the above problems.
It is a further object of the present invention to provide a novel ion-implantation apparatus capable o:f suppressing the shift of the ion-implantation when the ion-beam is irradiated onto the resist over the semiconductor wafer.
It is a still further object of the present invention to provide a novel method of ion-implantation free from the above problems.
It is yet a further object of the present invention to provide a novel method of ion-implantation for suppressing the shift of the ion-implantation when the ion-beam is irradiated onto the resist over the semiconductor wafer.
The present invention provides an ion-implantation apparatus comprising: a chamber; and a pressure controller for maintaining an internal pressure of the chamber at not less than 1E-4 Torr during an ion-implantation process.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.